The present invention relates to a high frequency resonator for the acceleration of heavy ions in an accelerator, e.g. a heavy ion accelerator operating at low frequency, of the type having a cylindrical resonator housing whose ends are provided with walls, and an even number, equal to at least four, of elongate conducting current collectors inside the housing, the current collectors being spaced symmetrically around a beam path extending along the longitudinal axis of the housing, with every second current collector being connected, via one of its ends, to the inlet end of the housing and the intervening collectors being similarly connected to the outlet end of the housing.
The purpose of any hf resonator of an accelerator is to feed a hf voltage U at the frequency f to a quasi-periodic electrode system (hereunder "duty system") placed in a high vacuum. The duty system can be considered to behave electrically like a capacitance C' per unit length and to have an effective length 1, resulting in a capacitance of C=C'.times.1. Reactive currents flowing into this capacitance must be delivered by the resonator. These currents together with other capacitive reactive currents produce a magnetic field H and a corresponding magnetic flux .PHI. which in turn generates, by its variation as a function of time, the voltage U. This will be described later with reference to FIG. 1.
This process is not free of energy dissipation. An effective hf power has to be supplied to the resonator via a feeding device to generate a voltage U.sub.1 on a supply line having a matched wave impedance Z. Generally, in the direction of the supply line there will be a vacuum window.
Such a resonator may also be considered as a resonance transformer having a voltage transmission ratio U/U.sub.1. The transmission energy loss P.sub.V can be defined as P.sub.V =U.sup.2 /2R.sub.p, where R.sub.p is the resonance resistance. Transmission ratio and resonance resistance are in general indefinite quantities, since one only rarely succeeds in generating a sufficiently homogeneous voltage distribution at the duty system.
A hf resonator of the type described above is known in the art, but presents several disadvantages.